Grating-assisted autofocus device and autofocusing method for an imaging device

摘要

There is provided an autofocus device for an imaging device which has an imaging lens system with a first focal plane, an object stage for holding an object and a first movement module for the relative movement of object stage and imaging lens system, wherein the autofocus device comprises an image-recording module with a second focal plane the position of which relative to the first focal plane is known,
a second movement module for the relative movement of object stage and image-recording module, a focus module for producing a two-dimensional, intensity-modulated focusing image in a focus module plane which intersects the second focal plane and a control module which controls the image-recording module for focusing the imaging device, which then records a first two-dimensional image of the object together with the focusing image during a predetermined first exposure time, and wherein the control module, using the first two-dimensional image recorded by means of the image-recording module and taking into account the relative position of the first and second focal plane, evaluates the required changes in distance between the object stage and the imaging lens system and controls the first movement module such that the evaluated change in distance is carried out, wherein the control module controls the second movement module such that, during the first exposure time for recording the first two-dimensional image, the object stage is moved relative to the image-recording module in a plane parallel to the second focal plane.

主权项

1. An autofocus device for an imaging device, which has an imaging lens system with a first focal plane, an object stage for holding an object and a first movement module for the relative movement of object stage and imaging lens system, wherein the autofocus device comprises:
an image-recording module with a second focal plane the position of which relative to the first focal plane is known, a second movement module for the relative movement of object stage and image-recording module, a focus module for producing a two-dimensional, intensity-modulated focusing image in a focus module plane which intersects the second focal plane, and a control module which controls the image-recording module, which then records a first two-dimensional image of the object together with the focusing image during a predetermined first exposure time period, and wherein the control module, using the first two-dimensional image recorded by means of the image-recording module and taking into account the relative position of the first and second focal planes, evaluates the required change in distance between the object stage and the imaging lens system and controls the first movement module such that the evaluated change in distance is carried out for focusing the imaging device, wherein the control module is configured to control the second movement module such that, during the first exposure time period for recording the first two-dimensional image, the object stage is moved relative to the image-recording module in a plane parallel to the second focal plane.